drbd: Introduce "peer_device" object between "device" and "connection"

In a setup where a device (aka volume) can replicate to multiple peers and one
connection can be shared between multiple devices, we need separate objects to
represent devices on peer nodes and network connections.

As a first step to introduce multiple connections per device, give each
drbd_device object a single drbd_peer_device object which connects it to a
drbd_connection object.

Signed-off-by: Andreas Gruenbacher <agruen@linbit.com>
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>

1 files changed, 123 insertions, 123 deletions

diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index 42dbf5d..e08e99f 100644
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -221,9 +221,9 @@ static void drbd_kick_lo_and_reclaim_net(struct drbd_device *device)
 	LIST_HEAD(reclaimed);
 	struct drbd_peer_request *peer_req, *t;
 
-	spin_lock_irq(&device->connection->req_lock);
+	spin_lock_irq(&first_peer_device(device)->connection->req_lock);
 	reclaim_finished_net_peer_reqs(device, &reclaimed);
-	spin_unlock_irq(&device->connection->req_lock);
+	spin_unlock_irq(&first_peer_device(device)->connection->req_lock);
 
 	list_for_each_entry_safe(peer_req, t, &reclaimed, w.list)
 		drbd_free_net_peer_req(device, peer_req);
@@ -252,7 +252,7 @@ struct page *drbd_alloc_pages(struct drbd_device *device, unsigned int number,
 	/* Yes, we may run up to @number over max_buffers. If we
 	 * follow it strictly, the admin will get it wrong anyways. */
 	rcu_read_lock();
-	nc = rcu_dereference(device->connection->net_conf);
+	nc = rcu_dereference(first_peer_device(device)->connection->net_conf);
 	mxb = nc ? nc->max_buffers : 1000000;
 	rcu_read_unlock();
 
@@ -288,7 +288,7 @@ struct page *drbd_alloc_pages(struct drbd_device *device, unsigned int number,
 }
 
 /* Must not be used from irq, as that may deadlock: see drbd_alloc_pages.
- * Is also used from inside an other spin_lock_irq(&device->connection->req_lock);
+ * Is also used from inside an other spin_lock_irq(&first_peer_device(device)->connection->req_lock);
  * Either links the page chain back to the global pool,
  * or returns all pages to the system. */
 static void drbd_free_pages(struct drbd_device *device, struct page *page, int is_net)
@@ -396,9 +396,9 @@ int drbd_free_peer_reqs(struct drbd_device *device, struct list_head *list)
 	int count = 0;
 	int is_net = list == &device->net_ee;
 
-	spin_lock_irq(&device->connection->req_lock);
+	spin_lock_irq(&first_peer_device(device)->connection->req_lock);
 	list_splice_init(list, &work_list);
-	spin_unlock_irq(&device->connection->req_lock);
+	spin_unlock_irq(&first_peer_device(device)->connection->req_lock);
 
 	list_for_each_entry_safe(peer_req, t, &work_list, w.list) {
 		__drbd_free_peer_req(device, peer_req, is_net);
@@ -417,10 +417,10 @@ static int drbd_finish_peer_reqs(struct drbd_device *device)
 	struct drbd_peer_request *peer_req, *t;
 	int err = 0;
 
-	spin_lock_irq(&device->connection->req_lock);
+	spin_lock_irq(&first_peer_device(device)->connection->req_lock);
 	reclaim_finished_net_peer_reqs(device, &reclaimed);
 	list_splice_init(&device->done_ee, &work_list);
-	spin_unlock_irq(&device->connection->req_lock);
+	spin_unlock_irq(&first_peer_device(device)->connection->req_lock);
 
 	list_for_each_entry_safe(peer_req, t, &reclaimed, w.list)
 		drbd_free_net_peer_req(device, peer_req);
@@ -452,19 +452,19 @@ static void _drbd_wait_ee_list_empty(struct drbd_device *device,
 	 * and calling prepare_to_wait in the fast path */
 	while (!list_empty(head)) {
 		prepare_to_wait(&device->ee_wait, &wait, TASK_UNINTERRUPTIBLE);
-		spin_unlock_irq(&device->connection->req_lock);
+		spin_unlock_irq(&first_peer_device(device)->connection->req_lock);
 		io_schedule();
 		finish_wait(&device->ee_wait, &wait);
-		spin_lock_irq(&device->connection->req_lock);
+		spin_lock_irq(&first_peer_device(device)->connection->req_lock);
 	}
 }
 
 static void drbd_wait_ee_list_empty(struct drbd_device *device,
 				    struct list_head *head)
 {
-	spin_lock_irq(&device->connection->req_lock);
+	spin_lock_irq(&first_peer_device(device)->connection->req_lock);
 	_drbd_wait_ee_list_empty(device, head);
-	spin_unlock_irq(&device->connection->req_lock);
+	spin_unlock_irq(&first_peer_device(device)->connection->req_lock);
 }
 
 static int drbd_recv_short(struct socket *sock, void *buf, size_t size, int flags)
@@ -838,8 +838,8 @@ int drbd_connected(struct drbd_device *device)
 	atomic_set(&device->packet_seq, 0);
 	device->peer_seq = 0;
 
-	device->state_mutex = device->connection->agreed_pro_version < 100 ?
-		&device->connection->cstate_mutex :
+	device->state_mutex = first_peer_device(device)->connection->agreed_pro_version < 100 ?
+		&first_peer_device(device)->connection->cstate_mutex :
 		&device->own_state_mutex;
 
 	err = drbd_send_sync_param(device);
@@ -1492,18 +1492,18 @@ read_in_block(struct drbd_device *device, u64 id, sector_t sector,
 	struct drbd_peer_request *peer_req;
 	struct page *page;
 	int dgs, ds, err;
-	void *dig_in = device->connection->int_dig_in;
-	void *dig_vv = device->connection->int_dig_vv;
+	void *dig_in = first_peer_device(device)->connection->int_dig_in;
+	void *dig_vv = first_peer_device(device)->connection->int_dig_vv;
 	unsigned long *data;
 
 	dgs = 0;
-	if (device->connection->peer_integrity_tfm) {
-		dgs = crypto_hash_digestsize(device->connection->peer_integrity_tfm);
+	if (first_peer_device(device)->connection->peer_integrity_tfm) {
+		dgs = crypto_hash_digestsize(first_peer_device(device)->connection->peer_integrity_tfm);
 		/*
 		 * FIXME: Receive the incoming digest into the receive buffer
 		 *	  here, together with its struct p_data?
 		 */
-		err = drbd_recv_all_warn(device->connection, dig_in, dgs);
+		err = drbd_recv_all_warn(first_peer_device(device)->connection, dig_in, dgs);
 		if (err)
 			return NULL;
 		data_size -= dgs;
@@ -1539,7 +1539,7 @@ read_in_block(struct drbd_device *device, u64 id, sector_t sector,
 	page_chain_for_each(page) {
 		unsigned len = min_t(int, ds, PAGE_SIZE);
 		data = kmap(page);
-		err = drbd_recv_all_warn(device->connection, data, len);
+		err = drbd_recv_all_warn(first_peer_device(device)->connection, data, len);
 		if (drbd_insert_fault(device, DRBD_FAULT_RECEIVE)) {
 			dev_err(DEV, "Fault injection: Corrupting data on receive\n");
 			data[0] = data[0] ^ (unsigned long)-1;
@@ -1553,7 +1553,7 @@ read_in_block(struct drbd_device *device, u64 id, sector_t sector,
 	}
 
 	if (dgs) {
-		drbd_csum_ee(device, device->connection->peer_integrity_tfm, peer_req, dig_vv);
+		drbd_csum_ee(device, first_peer_device(device)->connection->peer_integrity_tfm, peer_req, dig_vv);
 		if (memcmp(dig_in, dig_vv, dgs)) {
 			dev_err(DEV, "Digest integrity check FAILED: %llus +%u\n",
 				(unsigned long long)sector, data_size);
@@ -1583,7 +1583,7 @@ static int drbd_drain_block(struct drbd_device *device, int data_size)
 	while (data_size) {
 		unsigned int len = min_t(int, data_size, PAGE_SIZE);
 
-		err = drbd_recv_all_warn(device->connection, data, len);
+		err = drbd_recv_all_warn(first_peer_device(device)->connection, data, len);
 		if (err)
 			break;
 		data_size -= len;
@@ -1600,13 +1600,13 @@ static int recv_dless_read(struct drbd_device *device, struct drbd_request *req,
 	struct bvec_iter iter;
 	struct bio *bio;
 	int dgs, err, expect;
-	void *dig_in = device->connection->int_dig_in;
-	void *dig_vv = device->connection->int_dig_vv;
+	void *dig_in = first_peer_device(device)->connection->int_dig_in;
+	void *dig_vv = first_peer_device(device)->connection->int_dig_vv;
 
 	dgs = 0;
-	if (device->connection->peer_integrity_tfm) {
-		dgs = crypto_hash_digestsize(device->connection->peer_integrity_tfm);
-		err = drbd_recv_all_warn(device->connection, dig_in, dgs);
+	if (first_peer_device(device)->connection->peer_integrity_tfm) {
+		dgs = crypto_hash_digestsize(first_peer_device(device)->connection->peer_integrity_tfm);
+		err = drbd_recv_all_warn(first_peer_device(device)->connection, dig_in, dgs);
 		if (err)
 			return err;
 		data_size -= dgs;
@@ -1622,7 +1622,7 @@ static int recv_dless_read(struct drbd_device *device, struct drbd_request *req,
 	bio_for_each_segment(bvec, bio, iter) {
 		void *mapped = kmap(bvec.bv_page) + bvec.bv_offset;
 		expect = min_t(int, data_size, bvec.bv_len);
-		err = drbd_recv_all_warn(device->connection, mapped, expect);
+		err = drbd_recv_all_warn(first_peer_device(device)->connection, mapped, expect);
 		kunmap(bvec.bv_page);
 		if (err)
 			return err;
@@ -1630,7 +1630,7 @@ static int recv_dless_read(struct drbd_device *device, struct drbd_request *req,
 	}
 
 	if (dgs) {
-		drbd_csum_bio(device, device->connection->peer_integrity_tfm, bio, dig_vv);
+		drbd_csum_bio(device, first_peer_device(device)->connection->peer_integrity_tfm, bio, dig_vv);
 		if (memcmp(dig_in, dig_vv, dgs)) {
 			dev_err(DEV, "Digest integrity check FAILED. Broken NICs?\n");
 			return -EINVAL;
@@ -1685,9 +1685,9 @@ static int recv_resync_read(struct drbd_device *device, sector_t sector, int dat
 
 	peer_req->w.cb = e_end_resync_block;
 
-	spin_lock_irq(&device->connection->req_lock);
+	spin_lock_irq(&first_peer_device(device)->connection->req_lock);
 	list_add(&peer_req->w.list, &device->sync_ee);
-	spin_unlock_irq(&device->connection->req_lock);
+	spin_unlock_irq(&first_peer_device(device)->connection->req_lock);
 
 	atomic_add(data_size >> 9, &device->rs_sect_ev);
 	if (drbd_submit_peer_request(device, peer_req, WRITE, DRBD_FAULT_RS_WR) == 0)
@@ -1695,9 +1695,9 @@ static int recv_resync_read(struct drbd_device *device, sector_t sector, int dat
 
 	/* don't care for the reason here */
 	dev_err(DEV, "submit failed, triggering re-connect\n");
-	spin_lock_irq(&device->connection->req_lock);
+	spin_lock_irq(&first_peer_device(device)->connection->req_lock);
 	list_del(&peer_req->w.list);
-	spin_unlock_irq(&device->connection->req_lock);
+	spin_unlock_irq(&first_peer_device(device)->connection->req_lock);
 
 	drbd_free_peer_req(device, peer_req);
 fail:
@@ -1736,9 +1736,9 @@ static int receive_DataReply(struct drbd_connection *connection, struct packet_i
 
 	sector = be64_to_cpu(p->sector);
 
-	spin_lock_irq(&device->connection->req_lock);
+	spin_lock_irq(&first_peer_device(device)->connection->req_lock);
 	req = find_request(device, &device->read_requests, p->block_id, sector, false, __func__);
-	spin_unlock_irq(&device->connection->req_lock);
+	spin_unlock_irq(&first_peer_device(device)->connection->req_lock);
 	if (unlikely(!req))
 		return -EIO;
 
@@ -1837,16 +1837,16 @@ static int e_end_block(struct drbd_work *w, int cancel)
 	/* we delete from the conflict detection hash _after_ we sent out the
 	 * P_WRITE_ACK / P_NEG_ACK, to get the sequence number right.  */
 	if (peer_req->flags & EE_IN_INTERVAL_TREE) {
-		spin_lock_irq(&device->connection->req_lock);
+		spin_lock_irq(&first_peer_device(device)->connection->req_lock);
 		D_ASSERT(!drbd_interval_empty(&peer_req->i));
 		drbd_remove_epoch_entry_interval(device, peer_req);
 		if (peer_req->flags & EE_RESTART_REQUESTS)
 			restart_conflicting_writes(device, sector, peer_req->i.size);
-		spin_unlock_irq(&device->connection->req_lock);
+		spin_unlock_irq(&first_peer_device(device)->connection->req_lock);
 	} else
 		D_ASSERT(drbd_interval_empty(&peer_req->i));
 
-	drbd_may_finish_epoch(device->connection, peer_req->epoch, EV_PUT + (cancel ? EV_CLEANUP : 0));
+	drbd_may_finish_epoch(first_peer_device(device)->connection, peer_req->epoch, EV_PUT + (cancel ? EV_CLEANUP : 0));
 
 	return err;
 }
@@ -1871,7 +1871,7 @@ static int e_send_superseded(struct drbd_work *w, int unused)
 
 static int e_send_retry_write(struct drbd_work *w, int unused)
 {
-	struct drbd_connection *connection = w->device->connection;
+	struct drbd_connection *connection = first_peer_device(w->device)->connection;
 
 	return e_send_ack(w, connection->agreed_pro_version >= 100 ?
 			     P_RETRY_WRITE : P_SUPERSEDED);
@@ -1896,7 +1896,7 @@ static void update_peer_seq(struct drbd_device *device, unsigned int peer_seq)
 {
 	unsigned int newest_peer_seq;
 
-	if (test_bit(RESOLVE_CONFLICTS, &device->connection->flags)) {
+	if (test_bit(RESOLVE_CONFLICTS, &first_peer_device(device)->connection->flags)) {
 		spin_lock(&device->peer_seq_lock);
 		newest_peer_seq = seq_max(device->peer_seq, peer_seq);
 		device->peer_seq = newest_peer_seq;
@@ -1918,7 +1918,7 @@ static bool overlapping_resync_write(struct drbd_device *device, struct drbd_pee
 	struct drbd_peer_request *rs_req;
 	bool rv = 0;
 
-	spin_lock_irq(&device->connection->req_lock);
+	spin_lock_irq(&first_peer_device(device)->connection->req_lock);
 	list_for_each_entry(rs_req, &device->sync_ee, w.list) {
 		if (overlaps(peer_req->i.sector, peer_req->i.size,
 			     rs_req->i.sector, rs_req->i.size)) {
@@ -1926,7 +1926,7 @@ static bool overlapping_resync_write(struct drbd_device *device, struct drbd_pee
 			break;
 		}
 	}
-	spin_unlock_irq(&device->connection->req_lock);
+	spin_unlock_irq(&first_peer_device(device)->connection->req_lock);
 
 	return rv;
 }
@@ -1958,7 +1958,7 @@ static int wait_for_and_update_peer_seq(struct drbd_device *device, const u32 pe
 	long timeout;
 	int ret = 0, tp;
 
-	if (!test_bit(RESOLVE_CONFLICTS, &device->connection->flags))
+	if (!test_bit(RESOLVE_CONFLICTS, &first_peer_device(device)->connection->flags))
 		return 0;
 
 	spin_lock(&device->peer_seq_lock);
@@ -1974,7 +1974,7 @@ static int wait_for_and_update_peer_seq(struct drbd_device *device, const u32 pe
 		}
 
 		rcu_read_lock();
-		tp = rcu_dereference(device->connection->net_conf)->two_primaries;
+		tp = rcu_dereference(first_peer_device(device)->connection->net_conf)->two_primaries;
 		rcu_read_unlock();
 
 		if (!tp)
@@ -1984,7 +1984,7 @@ static int wait_for_and_update_peer_seq(struct drbd_device *device, const u32 pe
 		prepare_to_wait(&device->seq_wait, &wait, TASK_INTERRUPTIBLE);
 		spin_unlock(&device->peer_seq_lock);
 		rcu_read_lock();
-		timeout = rcu_dereference(device->connection->net_conf)->ping_timeo*HZ/10;
+		timeout = rcu_dereference(first_peer_device(device)->connection->net_conf)->ping_timeo*HZ/10;
 		rcu_read_unlock();
 		timeout = schedule_timeout(timeout);
 		spin_lock(&device->peer_seq_lock);
@@ -2027,10 +2027,10 @@ static void fail_postponed_requests(struct drbd_device *device, sector_t sector,
 			continue;
 		req->rq_state &= ~RQ_POSTPONED;
 		__req_mod(req, NEG_ACKED, &m);
-		spin_unlock_irq(&device->connection->req_lock);
+		spin_unlock_irq(&first_peer_device(device)->connection->req_lock);
 		if (m.bio)
 			complete_master_bio(device, &m);
-		spin_lock_irq(&device->connection->req_lock);
+		spin_lock_irq(&first_peer_device(device)->connection->req_lock);
 		goto repeat;
 	}
 }
@@ -2038,7 +2038,7 @@ static void fail_postponed_requests(struct drbd_device *device, sector_t sector,
 static int handle_write_conflicts(struct drbd_device *device,
 				  struct drbd_peer_request *peer_req)
 {
-	struct drbd_connection *connection = device->connection;
+	struct drbd_connection *connection = first_peer_device(device)->connection;
 	bool resolve_conflicts = test_bit(RESOLVE_CONFLICTS, &connection->flags);
 	sector_t sector = peer_req->i.sector;
 	const unsigned int size = peer_req->i.size;
@@ -2092,7 +2092,7 @@ static int handle_write_conflicts(struct drbd_device *device,
 			peer_req->w.cb = superseded ? e_send_superseded :
 						   e_send_retry_write;
 			list_add_tail(&peer_req->w.list, &device->done_ee);
-			wake_asender(device->connection);
+			wake_asender(first_peer_device(device)->connection);
 
 			err = -ENOENT;
 			goto out;
@@ -2121,7 +2121,7 @@ static int handle_write_conflicts(struct drbd_device *device,
 				 */
 				err = drbd_wait_misc(device, &req->i);
 				if (err) {
-					_conn_request_state(device->connection,
+					_conn_request_state(first_peer_device(device)->connection,
 							    NS(conn, C_TIMEOUT),
 							    CS_HARD);
 					fail_postponed_requests(device, sector, size);
@@ -2204,17 +2204,17 @@ static int receive_Data(struct drbd_connection *connection, struct packet_info *
 	spin_unlock(&connection->epoch_lock);
 
 	rcu_read_lock();
-	tp = rcu_dereference(device->connection->net_conf)->two_primaries;
+	tp = rcu_dereference(first_peer_device(device)->connection->net_conf)->two_primaries;
 	rcu_read_unlock();
 	if (tp) {
 		peer_req->flags |= EE_IN_INTERVAL_TREE;
 		err = wait_for_and_update_peer_seq(device, peer_seq);
 		if (err)
 			goto out_interrupted;
-		spin_lock_irq(&device->connection->req_lock);
+		spin_lock_irq(&first_peer_device(device)->connection->req_lock);
 		err = handle_write_conflicts(device, peer_req);
 		if (err) {
-			spin_unlock_irq(&device->connection->req_lock);
+			spin_unlock_irq(&first_peer_device(device)->connection->req_lock);
 			if (err == -ENOENT) {
 				put_ldev(device);
 				return 0;
@@ -2223,17 +2223,17 @@ static int receive_Data(struct drbd_connection *connection, struct packet_info *
 		}
 	} else {
 		update_peer_seq(device, peer_seq);
-		spin_lock_irq(&device->connection->req_lock);
+		spin_lock_irq(&first_peer_device(device)->connection->req_lock);
 	}
 	list_add(&peer_req->w.list, &device->active_ee);
-	spin_unlock_irq(&device->connection->req_lock);
+	spin_unlock_irq(&first_peer_device(device)->connection->req_lock);
 
 	if (device->state.conn == C_SYNC_TARGET)
 		wait_event(device->ee_wait, !overlapping_resync_write(device, peer_req));
 
-	if (device->connection->agreed_pro_version < 100) {
+	if (first_peer_device(device)->connection->agreed_pro_version < 100) {
 		rcu_read_lock();
-		switch (rcu_dereference(device->connection->net_conf)->wire_protocol) {
+		switch (rcu_dereference(first_peer_device(device)->connection->net_conf)->wire_protocol) {
 		case DRBD_PROT_C:
 			dp_flags |= DP_SEND_WRITE_ACK;
 			break;
@@ -2271,10 +2271,10 @@ static int receive_Data(struct drbd_connection *connection, struct packet_info *
 
 	/* don't care for the reason here */
 	dev_err(DEV, "submit failed, triggering re-connect\n");
-	spin_lock_irq(&device->connection->req_lock);
+	spin_lock_irq(&first_peer_device(device)->connection->req_lock);
 	list_del(&peer_req->w.list);
 	drbd_remove_epoch_entry_interval(device, peer_req);
-	spin_unlock_irq(&device->connection->req_lock);
+	spin_unlock_irq(&first_peer_device(device)->connection->req_lock);
 	if (peer_req->flags & EE_CALL_AL_COMPLETE_IO)
 		drbd_al_complete_io(device, &peer_req->i);
 
@@ -2450,11 +2450,11 @@ static int receive_DataRequest(struct drbd_connection *connection, struct packet
 		peer_req->digest = di;
 		peer_req->flags |= EE_HAS_DIGEST;
 
-		if (drbd_recv_all(device->connection, di->digest, pi->size))
+		if (drbd_recv_all(first_peer_device(device)->connection, di->digest, pi->size))
 			goto out_free_e;
 
 		if (pi->cmd == P_CSUM_RS_REQUEST) {
-			D_ASSERT(device->connection->agreed_pro_version >= 89);
+			D_ASSERT(first_peer_device(device)->connection->agreed_pro_version >= 89);
 			peer_req->w.cb = w_e_end_csum_rs_req;
 			/* used in the sector offset progress display */
 			device->bm_resync_fo = BM_SECT_TO_BIT(sector);
@@ -2471,7 +2471,7 @@ static int receive_DataRequest(struct drbd_connection *connection, struct packet
 
 	case P_OV_REQUEST:
 		if (device->ov_start_sector == ~(sector_t)0 &&
-		    device->connection->agreed_pro_version >= 90) {
+		    first_peer_device(device)->connection->agreed_pro_version >= 90) {
 			unsigned long now = jiffies;
 			int i;
 			device->ov_start_sector = sector;
@@ -2525,18 +2525,18 @@ submit_for_resync:
 
 submit:
 	inc_unacked(device);
-	spin_lock_irq(&device->connection->req_lock);
+	spin_lock_irq(&first_peer_device(device)->connection->req_lock);
 	list_add_tail(&peer_req->w.list, &device->read_ee);
-	spin_unlock_irq(&device->connection->req_lock);
+	spin_unlock_irq(&first_peer_device(device)->connection->req_lock);
 
 	if (drbd_submit_peer_request(device, peer_req, READ, fault_type) == 0)
 		return 0;
 
 	/* don't care for the reason here */
 	dev_err(DEV, "submit failed, triggering re-connect\n");
-	spin_lock_irq(&device->connection->req_lock);
+	spin_lock_irq(&first_peer_device(device)->connection->req_lock);
 	list_del(&peer_req->w.list);
-	spin_unlock_irq(&device->connection->req_lock);
+	spin_unlock_irq(&first_peer_device(device)->connection->req_lock);
 	/* no drbd_rs_complete_io(), we are dropping the connection anyways */
 
 out_free_e:
@@ -2558,7 +2558,7 @@ static int drbd_asb_recover_0p(struct drbd_device *device) __must_hold(local)
 	ch_self = device->comm_bm_set;
 
 	rcu_read_lock();
-	after_sb_0p = rcu_dereference(device->connection->net_conf)->after_sb_0p;
+	after_sb_0p = rcu_dereference(first_peer_device(device)->connection->net_conf)->after_sb_0p;
 	rcu_read_unlock();
 	switch (after_sb_0p) {
 	case ASB_CONSENSUS:
@@ -2593,7 +2593,7 @@ static int drbd_asb_recover_0p(struct drbd_device *device) __must_hold(local)
 		     "Using discard-least-changes instead\n");
 	case ASB_DISCARD_ZERO_CHG:
 		if (ch_peer == 0 && ch_self == 0) {
-			rv = test_bit(RESOLVE_CONFLICTS, &device->connection->flags)
+			rv = test_bit(RESOLVE_CONFLICTS, &first_peer_device(device)->connection->flags)
 				? -1 : 1;
 			break;
 		} else {
@@ -2609,7 +2609,7 @@ static int drbd_asb_recover_0p(struct drbd_device *device) __must_hold(local)
 			rv =  1;
 		else /* ( ch_self == ch_peer ) */
 		     /* Well, then use something else. */
-			rv = test_bit(RESOLVE_CONFLICTS, &device->connection->flags)
+			rv = test_bit(RESOLVE_CONFLICTS, &first_peer_device(device)->connection->flags)
 				? -1 : 1;
 		break;
 	case ASB_DISCARD_LOCAL:
@@ -2628,7 +2628,7 @@ static int drbd_asb_recover_1p(struct drbd_device *device) __must_hold(local)
 	enum drbd_after_sb_p after_sb_1p;
 
 	rcu_read_lock();
-	after_sb_1p = rcu_dereference(device->connection->net_conf)->after_sb_1p;
+	after_sb_1p = rcu_dereference(first_peer_device(device)->connection->net_conf)->after_sb_1p;
 	rcu_read_unlock();
 	switch (after_sb_1p) {
 	case ASB_DISCARD_YOUNGER_PRI:
@@ -2681,7 +2681,7 @@ static int drbd_asb_recover_2p(struct drbd_device *device) __must_hold(local)
 	enum drbd_after_sb_p after_sb_2p;
 
 	rcu_read_lock();
-	after_sb_2p = rcu_dereference(device->connection->net_conf)->after_sb_2p;
+	after_sb_2p = rcu_dereference(first_peer_device(device)->connection->net_conf)->after_sb_2p;
 	rcu_read_unlock();
 	switch (after_sb_2p) {
 	case ASB_DISCARD_YOUNGER_PRI:
@@ -2777,7 +2777,7 @@ static int drbd_uuid_compare(struct drbd_device *device, int *rule_nr) __must_ho
 
 		if (device->p_uuid[UI_BITMAP] == (u64)0 && device->ldev->md.uuid[UI_BITMAP] != (u64)0) {
 
-			if (device->connection->agreed_pro_version < 91)
+			if (first_peer_device(device)->connection->agreed_pro_version < 91)
 				return -1091;
 
 			if ((device->ldev->md.uuid[UI_BITMAP] & ~((u64)1)) == (device->p_uuid[UI_HISTORY_START] & ~((u64)1)) &&
@@ -2800,7 +2800,7 @@ static int drbd_uuid_compare(struct drbd_device *device, int *rule_nr) __must_ho
 
 		if (device->ldev->md.uuid[UI_BITMAP] == (u64)0 && device->p_uuid[UI_BITMAP] != (u64)0) {
 
-			if (device->connection->agreed_pro_version < 91)
+			if (first_peer_device(device)->connection->agreed_pro_version < 91)
 				return -1091;
 
 			if ((device->ldev->md.uuid[UI_HISTORY_START] & ~((u64)1)) == (device->p_uuid[UI_BITMAP] & ~((u64)1)) &&
@@ -2833,7 +2833,7 @@ static int drbd_uuid_compare(struct drbd_device *device, int *rule_nr) __must_ho
 		case 1: /*  self_pri && !peer_pri */ return 1;
 		case 2: /* !self_pri &&  peer_pri */ return -1;
 		case 3: /*  self_pri &&  peer_pri */
-			dc = test_bit(RESOLVE_CONFLICTS, &device->connection->flags);
+			dc = test_bit(RESOLVE_CONFLICTS, &first_peer_device(device)->connection->flags);
 			return dc ? -1 : 1;
 		}
 	}
@@ -2846,14 +2846,14 @@ static int drbd_uuid_compare(struct drbd_device *device, int *rule_nr) __must_ho
 	*rule_nr = 51;
 	peer = device->p_uuid[UI_HISTORY_START] & ~((u64)1);
 	if (self == peer) {
-		if (device->connection->agreed_pro_version < 96 ?
+		if (first_peer_device(device)->connection->agreed_pro_version < 96 ?
 		    (device->ldev->md.uuid[UI_HISTORY_START] & ~((u64)1)) ==
 		    (device->p_uuid[UI_HISTORY_START + 1] & ~((u64)1)) :
 		    peer + UUID_NEW_BM_OFFSET == (device->p_uuid[UI_BITMAP] & ~((u64)1))) {
 			/* The last P_SYNC_UUID did not get though. Undo the last start of
 			   resync as sync source modifications of the peer's UUIDs. */
 
-			if (device->connection->agreed_pro_version < 91)
+			if (first_peer_device(device)->connection->agreed_pro_version < 91)
 				return -1091;
 
 			device->p_uuid[UI_BITMAP] = device->p_uuid[UI_HISTORY_START];
@@ -2883,14 +2883,14 @@ static int drbd_uuid_compare(struct drbd_device *device, int *rule_nr) __must_ho
 	*rule_nr = 71;
 	self = device->ldev->md.uuid[UI_HISTORY_START] & ~((u64)1);
 	if (self == peer) {
-		if (device->connection->agreed_pro_version < 96 ?
+		if (first_peer_device(device)->connection->agreed_pro_version < 96 ?
 		    (device->ldev->md.uuid[UI_HISTORY_START + 1] & ~((u64)1)) ==
 		    (device->p_uuid[UI_HISTORY_START] & ~((u64)1)) :
 		    self + UUID_NEW_BM_OFFSET == (device->ldev->md.uuid[UI_BITMAP] & ~((u64)1))) {
 			/* The last P_SYNC_UUID did not get though. Undo the last start of
 			   resync as sync source modifications of our UUIDs. */
 
-			if (device->connection->agreed_pro_version < 91)
+			if (first_peer_device(device)->connection->agreed_pro_version < 91)
 				return -1091;
 
 			__drbd_uuid_set(device, UI_BITMAP, device->ldev->md.uuid[UI_HISTORY_START]);
@@ -2982,7 +2982,7 @@ static enum drbd_conns drbd_sync_handshake(struct drbd_device *device, enum drbd
 		drbd_khelper(device, "initial-split-brain");
 
 	rcu_read_lock();
-	nc = rcu_dereference(device->connection->net_conf);
+	nc = rcu_dereference(first_peer_device(device)->connection->net_conf);
 
 	if (hg == 100 || (hg == -100 && nc->always_asbp)) {
 		int pcount = (device->state.role == R_PRIMARY)
@@ -3057,7 +3057,7 @@ static enum drbd_conns drbd_sync_handshake(struct drbd_device *device, enum drbd
 		}
 	}
 
-	if (tentative || test_bit(CONN_DRY_RUN, &device->connection->flags)) {
+	if (tentative || test_bit(CONN_DRY_RUN, &first_peer_device(device)->connection->flags)) {
 		if (hg == 0)
 			dev_info(DEV, "dry-run connect: No resync, would become Connected immediately.\n");
 		else
@@ -3361,17 +3361,17 @@ static int receive_SyncParam(struct drbd_connection *connection, struct packet_i
 	p = pi->data;
 	memset(p->verify_alg, 0, 2 * SHARED_SECRET_MAX);
 
-	err = drbd_recv_all(device->connection, p, header_size);
+	err = drbd_recv_all(first_peer_device(device)->connection, p, header_size);
 	if (err)
 		return err;
 
-	mutex_lock(&device->connection->conf_update);
-	old_net_conf = device->connection->net_conf;
+	mutex_lock(&first_peer_device(device)->connection->conf_update);
+	old_net_conf = first_peer_device(device)->connection->net_conf;
 	if (get_ldev(device)) {
 		new_disk_conf = kzalloc(sizeof(struct disk_conf), GFP_KERNEL);
 		if (!new_disk_conf) {
 			put_ldev(device);
-			mutex_unlock(&device->connection->conf_update);
+			mutex_unlock(&first_peer_device(device)->connection->conf_update);
 			dev_err(DEV, "Allocation of new disk_conf failed\n");
 			return -ENOMEM;
 		}
@@ -3392,7 +3392,7 @@ static int receive_SyncParam(struct drbd_connection *connection, struct packet_i
 				goto reconnect;
 			}
 
-			err = drbd_recv_all(device->connection, p->verify_alg, data_size);
+			err = drbd_recv_all(first_peer_device(device)->connection, p->verify_alg, data_size);
 			if (err)
 				goto reconnect;
 			/* we expect NUL terminated string */
@@ -3466,15 +3466,15 @@ static int receive_SyncParam(struct drbd_connection *connection, struct packet_i
 			if (verify_tfm) {
 				strcpy(new_net_conf->verify_alg, p->verify_alg);
 				new_net_conf->verify_alg_len = strlen(p->verify_alg) + 1;
-				crypto_free_hash(device->connection->verify_tfm);
-				device->connection->verify_tfm = verify_tfm;
+				crypto_free_hash(first_peer_device(device)->connection->verify_tfm);
+				first_peer_device(device)->connection->verify_tfm = verify_tfm;
 				dev_info(DEV, "using verify-alg: \"%s\"\n", p->verify_alg);
 			}
 			if (csums_tfm) {
 				strcpy(new_net_conf->csums_alg, p->csums_alg);
 				new_net_conf->csums_alg_len = strlen(p->csums_alg) + 1;
-				crypto_free_hash(device->connection->csums_tfm);
-				device->connection->csums_tfm = csums_tfm;
+				crypto_free_hash(first_peer_device(device)->connection->csums_tfm);
+				first_peer_device(device)->connection->csums_tfm = csums_tfm;
 				dev_info(DEV, "using csums-alg: \"%s\"\n", p->csums_alg);
 			}
 			rcu_assign_pointer(connection->net_conf, new_net_conf);
@@ -3491,7 +3491,7 @@ static int receive_SyncParam(struct drbd_connection *connection, struct packet_i
 		rcu_assign_pointer(device->rs_plan_s, new_plan);
 	}
 
-	mutex_unlock(&device->connection->conf_update);
+	mutex_unlock(&first_peer_device(device)->connection->conf_update);
 	synchronize_rcu();
 	if (new_net_conf)
 		kfree(old_net_conf);
@@ -3505,7 +3505,7 @@ reconnect:
 		put_ldev(device);
 		kfree(new_disk_conf);
 	}
-	mutex_unlock(&device->connection->conf_update);
+	mutex_unlock(&first_peer_device(device)->connection->conf_update);
 	return -EIO;
 
 disconnect:
@@ -3514,13 +3514,13 @@ disconnect:
 		put_ldev(device);
 		kfree(new_disk_conf);
 	}
-	mutex_unlock(&device->connection->conf_update);
+	mutex_unlock(&first_peer_device(device)->connection->conf_update);
 	/* just for completeness: actually not needed,
 	 * as this is not reached if csums_tfm was ok. */
 	crypto_free_hash(csums_tfm);
 	/* but free the verify_tfm again, if csums_tfm did not work out */
 	crypto_free_hash(verify_tfm);
-	conn_request_state(device->connection, NS(conn, C_DISCONNECTING), CS_HARD);
+	conn_request_state(first_peer_device(device)->connection, NS(conn, C_DISCONNECTING), CS_HARD);
 	return -EIO;
 }
 
@@ -3579,7 +3579,7 @@ static int receive_sizes(struct drbd_connection *connection, struct packet_info
 		    device->state.disk >= D_OUTDATED &&
 		    device->state.conn < C_CONNECTED) {
 			dev_err(DEV, "The peer's disk size is too small!\n");
-			conn_request_state(device->connection, NS(conn, C_DISCONNECTING), CS_HARD);
+			conn_request_state(first_peer_device(device)->connection, NS(conn, C_DISCONNECTING), CS_HARD);
 			put_ldev(device);
 			return -EIO;
 		}
@@ -3594,13 +3594,13 @@ static int receive_sizes(struct drbd_connection *connection, struct packet_info
 				return -ENOMEM;
 			}
 
-			mutex_lock(&device->connection->conf_update);
+			mutex_lock(&first_peer_device(device)->connection->conf_update);
 			old_disk_conf = device->ldev->disk_conf;
 			*new_disk_conf = *old_disk_conf;
 			new_disk_conf->disk_size = p_usize;
 
 			rcu_assign_pointer(device->ldev->disk_conf, new_disk_conf);
-			mutex_unlock(&device->connection->conf_update);
+			mutex_unlock(&first_peer_device(device)->connection->conf_update);
 			synchronize_rcu();
 			kfree(old_disk_conf);
 
@@ -3687,14 +3687,14 @@ static int receive_uuids(struct drbd_connection *connection, struct packet_info
 	    (device->ed_uuid & ~((u64)1)) != (p_uuid[UI_CURRENT] & ~((u64)1))) {
 		dev_err(DEV, "Can only connect to data with current UUID=%016llX\n",
 		    (unsigned long long)device->ed_uuid);
-		conn_request_state(device->connection, NS(conn, C_DISCONNECTING), CS_HARD);
+		conn_request_state(first_peer_device(device)->connection, NS(conn, C_DISCONNECTING), CS_HARD);
 		return -EIO;
 	}
 
 	if (get_ldev(device)) {
 		int skip_initial_sync =
 			device->state.conn == C_CONNECTED &&
-			device->connection->agreed_pro_version >= 90 &&
+			first_peer_device(device)->connection->agreed_pro_version >= 90 &&
 			device->ldev->md.uuid[UI_CURRENT] == UUID_JUST_CREATED &&
 			(p_uuid[UI_FLAGS] & 8);
 		if (skip_initial_sync) {
@@ -3777,7 +3777,7 @@ static int receive_req_state(struct drbd_connection *connection, struct packet_i
 	mask.i = be32_to_cpu(p->mask);
 	val.i = be32_to_cpu(p->val);
 
-	if (test_bit(RESOLVE_CONFLICTS, &device->connection->flags) &&
+	if (test_bit(RESOLVE_CONFLICTS, &first_peer_device(device)->connection->flags) &&
 	    mutex_is_locked(device->state_mutex)) {
 		drbd_send_sr_reply(device, SS_CONCURRENT_ST_CHG);
 		return 0;
@@ -3839,10 +3839,10 @@ static int receive_state(struct drbd_connection *connection, struct packet_info
 		dev_info(DEV, "real peer disk state = %s\n", drbd_disk_str(real_peer_disk));
 	}
 
-	spin_lock_irq(&device->connection->req_lock);
+	spin_lock_irq(&first_peer_device(device)->connection->req_lock);
  retry:
 	os = ns = drbd_read_state(device);
-	spin_unlock_irq(&device->connection->req_lock);
+	spin_unlock_irq(&first_peer_device(device)->connection->req_lock);
 
 	/* If some other part of the code (asender thread, timeout)
 	 * already decided to close the connection again,
@@ -3936,16 +3936,16 @@ static int receive_state(struct drbd_connection *connection, struct packet_info
 				peer_state.disk = D_DISKLESS;
 				real_peer_disk = D_DISKLESS;
 			} else {
-				if (test_and_clear_bit(CONN_DRY_RUN, &device->connection->flags))
+				if (test_and_clear_bit(CONN_DRY_RUN, &first_peer_device(device)->connection->flags))
 					return -EIO;
 				D_ASSERT(os.conn == C_WF_REPORT_PARAMS);
-				conn_request_state(device->connection, NS(conn, C_DISCONNECTING), CS_HARD);
+				conn_request_state(first_peer_device(device)->connection, NS(conn, C_DISCONNECTING), CS_HARD);
 				return -EIO;
 			}
 		}
 	}
 
-	spin_lock_irq(&device->connection->req_lock);
+	spin_lock_irq(&first_peer_device(device)->connection->req_lock);
 	if (os.i != drbd_read_state(device).i)
 		goto retry;
 	clear_bit(CONSIDER_RESYNC, &device->flags);
@@ -3959,20 +3959,20 @@ static int receive_state(struct drbd_connection *connection, struct packet_info
 	    test_bit(NEW_CUR_UUID, &device->flags)) {
 		/* Do not allow tl_restart(RESEND) for a rebooted peer. We can only allow this
 		   for temporal network outages! */
-		spin_unlock_irq(&device->connection->req_lock);
+		spin_unlock_irq(&first_peer_device(device)->connection->req_lock);
 		dev_err(DEV, "Aborting Connect, can not thaw IO with an only Consistent peer\n");
-		tl_clear(device->connection);
+		tl_clear(first_peer_device(device)->connection);
 		drbd_uuid_new_current(device);
 		clear_bit(NEW_CUR_UUID, &device->flags);
-		conn_request_state(device->connection, NS2(conn, C_PROTOCOL_ERROR, susp, 0), CS_HARD);
+		conn_request_state(first_peer_device(device)->connection, NS2(conn, C_PROTOCOL_ERROR, susp, 0), CS_HARD);
 		return -EIO;
 	}
 	rv = _drbd_set_state(device, ns, cs_flags, NULL);
 	ns = drbd_read_state(device);
-	spin_unlock_irq(&device->connection->req_lock);
+	spin_unlock_irq(&first_peer_device(device)->connection->req_lock);
 
 	if (rv < SS_SUCCESS) {
-		conn_request_state(device->connection, NS(conn, C_DISCONNECTING), CS_HARD);
+		conn_request_state(first_peer_device(device)->connection, NS(conn, C_DISCONNECTING), CS_HARD);
 		return -EIO;
 	}
 
@@ -4038,7 +4038,7 @@ receive_bitmap_plain(struct drbd_device *device, unsigned int size,
 		     unsigned long *p, struct bm_xfer_ctx *c)
 {
 	unsigned int data_size = DRBD_SOCKET_BUFFER_SIZE -
-				 drbd_header_size(device->connection);
+				 drbd_header_size(first_peer_device(device)->connection);
 	unsigned int num_words = min_t(size_t, data_size / sizeof(*p),
 				       c->bm_words - c->word_offset);
 	unsigned int want = num_words * sizeof(*p);
@@ -4050,7 +4050,7 @@ receive_bitmap_plain(struct drbd_device *device, unsigned int size,
 	}
 	if (want == 0)
 		return 0;
-	err = drbd_recv_all(device->connection, p, want);
+	err = drbd_recv_all(first_peer_device(device)->connection, p, want);
 	if (err)
 		return err;
 
@@ -4168,7 +4168,7 @@ decode_bitmap_c(struct drbd_device *device,
 	 * during all our tests. */
 
 	dev_err(DEV, "receive_bitmap_c: unknown encoding %u\n", p->encoding);
-	conn_request_state(device->connection, NS(conn, C_PROTOCOL_ERROR), CS_HARD);
+	conn_request_state(first_peer_device(device)->connection, NS(conn, C_PROTOCOL_ERROR), CS_HARD);
 	return -EIO;
 }
 
@@ -4176,7 +4176,7 @@ void INFO_bm_xfer_stats(struct drbd_device *device,
 		const char *direction, struct bm_xfer_ctx *c)
 {
 	/* what would it take to transfer it "plaintext" */
-	unsigned int header_size = drbd_header_size(device->connection);
+	unsigned int header_size = drbd_header_size(first_peer_device(device)->connection);
 	unsigned int data_size = DRBD_SOCKET_BUFFER_SIZE - header_size;
 	unsigned int plain =
 		header_size * (DIV_ROUND_UP(c->bm_words, data_size) + 1) +
@@ -4253,7 +4253,7 @@ static int receive_bitmap(struct drbd_connection *connection, struct packet_info
 				err = -EIO;
 				goto out;
 			}
-			err = drbd_recv_all(device->connection, p, pi->size);
+			err = drbd_recv_all(first_peer_device(device)->connection, p, pi->size);
 			if (err)
 			       goto out;
 			err = decode_bitmap_c(device, p, &c, pi->size);
@@ -4271,7 +4271,7 @@ static int receive_bitmap(struct drbd_connection *connection, struct packet_info
 				goto out;
 			break;
 		}
-		err = drbd_recv_header(device->connection, pi);
+		err = drbd_recv_header(first_peer_device(device)->connection, pi);
 		if (err)
 			goto out;
 	}
@@ -4491,11 +4491,11 @@ static int drbd_disconnected(struct drbd_device *device)
 	unsigned int i;
 
 	/* wait for current activity to cease. */
-	spin_lock_irq(&device->connection->req_lock);
+	spin_lock_irq(&first_peer_device(device)->connection->req_lock);
 	_drbd_wait_ee_list_empty(device, &device->active_ee);
 	_drbd_wait_ee_list_empty(device, &device->sync_ee);
 	_drbd_wait_ee_list_empty(device, &device->read_ee);
-	spin_unlock_irq(&device->connection->req_lock);
+	spin_unlock_irq(&first_peer_device(device)->connection->req_lock);
 
 	/* We do not have data structures that would allow us to
 	 * get the rs_pending_cnt down to 0 again.
@@ -4536,7 +4536,7 @@ static int drbd_disconnected(struct drbd_device *device)
 	device->p_uuid = NULL;
 
 	if (!drbd_suspended(device))
-		tl_clear(device->connection);
+		tl_clear(first_peer_device(device)->connection);
 
 	drbd_md_sync(device);
 
@@ -4937,7 +4937,7 @@ static int got_IsInSync(struct drbd_connection *connection, struct packet_info *
 	if (!device)
 		return -EIO;
 
-	D_ASSERT(device->connection->agreed_pro_version >= 89);
+	D_ASSERT(first_peer_device(device)->connection->agreed_pro_version >= 89);
 
 	update_peer_seq(device, be32_to_cpu(p->seq_num));
 
@@ -4962,14 +4962,14 @@ validate_req_change_req_state(struct drbd_device *device, u64 id, sector_t secto
 	struct drbd_request *req;
 	struct bio_and_error m;
 
-	spin_lock_irq(&device->connection->req_lock);
+	spin_lock_irq(&first_peer_device(device)->connection->req_lock);
 	req = find_request(device, root, id, sector, missing_ok, func);
 	if (unlikely(!req)) {
-		spin_unlock_irq(&device->connection->req_lock);
+		spin_unlock_irq(&first_peer_device(device)->connection->req_lock);
 		return -EIO;
 	}
 	__req_mod(req, what, &m);
-	spin_unlock_irq(&device->connection->req_lock);
+	spin_unlock_irq(&first_peer_device(device)->connection->req_lock);
 
 	if (m.bio)
 		complete_master_bio(device, &m);
@@ -5169,7 +5169,7 @@ static int got_OVResult(struct drbd_connection *connection, struct packet_info *
 		if (w) {
 			w->cb = w_ov_finished;
 			w->device = device;
-			drbd_queue_work(&device->connection->sender_work, w);
+			drbd_queue_work(&first_peer_device(device)->connection->sender_work, w);
 		} else {
 			dev_err(DEV, "kmalloc(w) failed.");
 			ov_out_of_sync_print(device);